Circuit for enciphering device

ABSTRACT

There is disclosed a circuit for an enciphering device which couples in character element fashion the multidigit coded signals of a first input location with the multidigit coded signals of a second input location, comprising at least one character detector operatively associated with a key character generator, which upon the occurrence of a first predetermined character combination at its output is influenced such that it offers a different character combination, and wherein at least one charaCter detector is arranged at the output of the circuit which upon the occurrence of a second predetermined character combination causes the key character generator to deliver a predetermined yet always similar character combination before the second predetermined character combination appearing at the output is released.

o 1: Ned States Patent 1 1 1 1 3,725,579 Sturzinger 1 Apr. 3, 1973 [54] CIRCUIT FOR ENCIPHERING DEVICE 3,229,037 1/1966 Sturzinger et a1. ..178 22 [75] Inventor: Oskar Edwin Sturzinger, Baar,

Switzerland Primary Exammer-Ben am1n A. Borchelt Assistant ExaminerH. A. Birmiel 1 Asslgneer Alma" Europalsche d Attorney-Ostrolenk, Faber, Gerb & Soffen sgesellschaft, Vaduz, L1echtenste1n 22 Filed: Mar. 10, 1971 ABSTRACT [21] Appl. No.: 122,969 There is disclosed a circuit for an enciphering device which couples in character element fashion the multidigit coded signals of a first input location with the [30] Forelg Apphcamm Pnomy Data multidigit coded signals of a second input location, Mar. 16, 1970 Switzerland 3922 70 comprising at least one Character detector Operatively associated with a key character generator, which upon [52] 11.8. C1. ..178/22 the cc rrence of a first predetermined character [51] Int. Cl. ..H04l 9/00, G09c 1/00 Combination at its output is influenced such that it of- [58] Field of Search ..178/22 fers a different character combination, and wherein at least one charaCter detector is arranged at the output [56] References Cited of the circuit which upon the occurrence of a second predetermined character combination causes the key UNITED STATES PATENTS character generator to deliver a predetermined yet al- 3,546,380 12/1970 Sturzinger ..17s/22 y similar character combination before the second 2,897,268 7/1959 Bacon et a1 ..178/22 predetermined character combination appearing at 2,406,829 9/1946 Haglund et al. ....l78/22 the output is released. 2,874,215 2/1959 Zenner ....178/22 2,406,023 8/1946 Locke ..l78/22 2 Claims, 3 Drawing Figures KEY CHARACTER GENERATOR F 1- I l r 1 l l 1 F I l l l l 1 l l 2 l I l 1 I l I CHARACTER l DETECTORS I I INPUT] OUTPUT l I I 4 I 5 e l 7 I l MIXER I l .1

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I O a o 1 m {I 5 X E X 2 T r f/ CIRCUIT FOR ENCIPHERING DEVICE BACKGROUND OF THE INVENTION The present invention relates to improved circuitry for enciphering devices.

Enciphering techniques which are conventional at the present time operate in many instances in sucha manner that they are accommodated to teleprinter operations. This has the advantage that devices designed according to these techniques can be directly coupled with the international telecommunication circuitry; or that at least the five unit-perforated tapes which are utilized in teleprinting can serve as the coupling element between the teleprinter network and the enciphering device.

In international teleprinter networks, there is used a dual (binary) code employing five digit character representation, resulting in 2 32 different combinations, the allocation or allotment of which has been determined by CCITT-Code 2.

In most instances for enciphering one proceeds such that from a key character generator of the type as has been described, forinstance, in Swiss Patent 362,555, now U. S. Pat. No. 3,006,081 for each text character A group there is interrogated a key character group, and

both information groups are multiplicatively mixed character-elementwise (exclusive OR combination). Thus, there appear the following operational rules:

It is apparent that the result in a five digit-dual (binary) code will again embrace all 32 combinations.

In international telecommunication networks, however, the group 0 0 0 0 is generally not permissible. Only after a momentary agreement between the relevant teleprinter organizations is such transmitted. In fact, it is even planned to generally block such and to be able to use such for service signaling purposes.

SUMMARY OF THE INVENTION The present invention therefore has for one of its primary objectives to provide a mixing technique of the above type for enciphering, and wherein by carrying out a directed influencing of the key character generator, there can however be achieved that only 31 different combinations appear at the transmission line.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a block circuit diagram of the inventive circuitry for an enciphering device;

FIG. 2 is a detailed illustration of an embodiment of the invention; and

FIG. 3 is a further detailed circuit diagram or a further embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in FIGS. 1 and 2 there is illustrated a key character generator 1 which delivers its information in the form of a multidigit coded-dual (binary) code, in the present case five digit code, to scontacts. Reference numeral 2 represents a character detector and reference numeral 5 a mixing stage which, in the illustration of FIG. 2, has been deleted for purposes of preserving clarity in illustration.

Reference numeral 6 indicates a further character detector, whereas reference numeral 4 indicates an input or primary storage and reference numeral 7 an output or secondary storage. Depending upon the manner of use of the circuitry additional non-illustrated input and output means are required. During line operation, the input storage 4 has connected in front thereof a so-called receiver distributor (series-parallel converter), and following the output storage 7 there is arranged a transmitter distributor (parallel-series converter).

During non-line bound operation, the input storage 4 can be controlled, for instance, by a keyboard, and the output storage 7 delivers its information to a perforated tape puncher. Various different mixed possibilities are conceivable: for instance, input via a keyboard and output at the line, or input via the line and output via the perforated tape puncher or printing mechanism (all of which prints the technical CCITT signals). It should always be remembered that one is working with the CCI'IT-code 2 or a code similar to such.

The key character generator 1 is advanced by one work step, for each text character to be processed, by means of a stepping transmitter or mechanism 8 (FIG.

2). Thus, the stepping transmitter 8 is triggered by appropriate switching means 10 each time there appears a character which is to be processed. For instance, these switching means can be a key contact which is common to all keys for the keyboard input.

The key character or code information offered by the generator 1 is represented by the position of the five contacts 5,, S the lower position corresponding to the binary L, the upper position to the 0.

The character input occurs by adjusting the contacts a, 2 by the input means, thus for instance the keyboard. Also here, the lower contact position corresponds to a binary L, the upper position to a 0. These contacts collectively form the so-called primary storage 4, since at such there is embodied the primary infedcharacter information.

If the contact n is closed by virtue of the action of the associated cam disk, which is driven by a suitable motor 9 in response to the commands of the switching means 10, then, depending upon the position of the just-mentioned contacts a e, of the primary storage 4 and the key character generator contacts s the relay coils F J will be selectively energized, which collectively form the secondary storage 7, since they contain the information of the mixing circuit which is to be delivered.

Therefore, a current for instance flows from the positive pole of a common voltage source (not illustrated for purposes of simplicity) via the relay G, s b,, n to the negative pole, referenced at 0 in FIG. 2. If at any time at one of the five parallel current circuits formed in this manner a left or right contact is in its opposite position from the others, then it will be apparent that no current flows and the corresponding relay is not energized. At this point there must be observed the heretofore mentioned logical operations which offer four possibilities for two results.

A self-holding contact f j is associated with each relay F J in such a manner that the energized relay can lock-in via these contacts and further via the contact n, in a self-holding state, even when the contact n is open. The secondary information is then available at the contacts f j;,, for a certain period of time. The switching means 10 initially has started the drive motor 9 which moves through one cycle, driving, through its output 9a, the cam disks of the contacts n;, and n.,, the closing times of which partially overlap.

After delivery of the secondary information to the secondary storage 7, the contact n opens so that the five mentioned relays fall back into the (upper) rest position O-position Naturally, instead of using the cam contacts, it is also conceivable to use relay contacts or other control means, all of which, together with the stepping transmitter 8, and for each text character which is to be processed, pass through a predetermined work cycle, which can be visualized as follows:

1. lnfeed of the text character into the primary storage input 4 and simultaneous triggering of the apparatus.

2. Preparing a key character by means of the key character generator 1.

3. Mixing and simultaneous infeed into the secondary storage 7 (controlled by the contact n 4. Storage of the secondary character in the secondary storage 7 (controlled by the contact n 5. Delivery of the secondary character by the secondary storage 7.

6. Extinguishing a secondary character (by the contact n,).

The relays F J, however, carry a further set of contacts f .j which are grouped together into a chain circuit to form the detector 6. It will be apparent that the combination where all five relays are in their rest state, causes the relay coil K to become energized. It is this which represents the combination O O 0 0 or CCITT No. 32. The contact K, actuated by the coil K, when in its actuated condition, now acts upon the key character generator in such a manner that its contacts s s for such work contact assume the lower position (LLLLL), corresponding to an enciphering without switching, that is, a clear text transmission.

The contacts s s which are connected together into a further chain forming the detector 2, operate parallel to the contacts s s,,,; it should be recognized that they cause energization of the relay coil 0 in their position L L L L L. The contact 0 associated with the coil 0, in its actuated condition operates in such a way upon the generator 1 that such offers a different key character. For instance, the stepping transmitter 8 can be caused to allow the generator 1 to travel further in a faster tempo until a key combination is offered which is different from L L L L L. Depending upon the operating principle of this key character generator, such can signify a more or less larger number of steps. However, the technology of today allows realization of such circuits, for instance in accordance with the already mentioned Swiss Patent 362,555 now U.S. Pat. No. 3,006,081, in which there can be ascertained for the poorest situation which might possibly be encountered the number of steps which must be travelled through, and from which there then can be derived the minimum necessary faster secondary side,

stepping speed, since of course everything must occur prior to the infeed storage of the secondary characters.

It should be clear that the position L L L L L of the contacts of the key character generator, brought about by the contact k,, is without effect upon the stepping transmitter because there is coupled in series with the contact 0 the rest contact k which in its actuated (open position) suppresses a possible rapid travel command.

It is apparent that because of the described circuitry, which of course can be completely electronic, hydraulic, or realized in another manner, the following operations can be realized:

1. The character combinations 0 0 0 0 0 never occur at the primary side. (This is evident from the definition of the CClTT-Alphabet No. 2, in which these combinations are of course blocked.)

2. The key character generator 1 never freely delivers as the product of its key character series the information L L L L L to the mixing stage (should such once occur then the generator travels further in a rapid tempo and is caused to offer a different combination).

3. Upon occurrence of the character 0 0 0 0 O at the then infeed storage thereof is prevented and instead of such the character offered to the primary side is introduced as clear text to the secondary storage. The key character generator 1 then positively delivers, and only then, the combination L L L L L.

Since the mixing occurs in the form of such modulo 2, it is apparent that for deciphering nothing more is necessary than once again enciphering with the momentary employed same key characters. The deciphering circuitry therefore is of exactly the same construction as the described enciphering circuitry.

The substitution technique for certain characters based upon this circuitry is not limited to multidigit dual (binary) coded characters. Thus, for instance, in a ternary system it is possible to operate with the following logical operation rules.

Clear Character Key Character Secret Character Inversion L J, Inversion J L, Inversion 0 0.

If the secret character is mixed according to this logical operation rule with the inverted key characters, then there again appears in accordance with the following table the original clear character:

Secret Original lnverted Deciphered Clear Character Kcy Character Kcy Character Text Character 1 L (L) J 0 2 J (L) J L 3 O (L) J J 4 J (J) L O 5 O (J) L L 6 L (J) L J 7 O (O) O O 8 L (O) O L 9 J (0) O J This operation therefore corresponds to deciphering.

It is apparent that the deciphered material again corresponds to the original clear characters according to the illustrated table.

It is now possible, with similar techniques, as already described, to prevent that, for instance, the combination 0 0 0 0 0 or another certain combination appears at the output. Likewise, similar means are possible for the key character generator, which again ensure that a certain key character combination is never introduced into the mixing stage.

The ternary logical operation is of interest for key character devices equipped with a printed output.

According to the international telegraph or telecommunication regulations coded messages can only consist of numberor letter-groups. Thus, it is possible to build key character devices which in a ternary three code system exhibit 3 27 character combinations: 26 of these are associated with the letters of the intemational alphabet. The combination, for instance, 0 0 0 is not used. The enciphering operation is carried out according to the mentioned logical operation rules with a three-position ternary signal. From what has been stated above, there is ensured that at the output only 26 letters appear. As concerns a ternary system the following can be stated:

The circuit is to be constructed in such a way that:

1. For a clear text input the combination 0 0 0 never appears (by simple elimination).

2. Upon the occurrence of the combination 0 0 0 at the key character transmitter such travels further or offers a different combination.

3. Upon the appearance of the combination 0 0 0 at the output there occurs an enciphering with 0 0 O and an inversion, as such has been illustrated with the following example:

Clear Character Key Character Secret Character 0 O 0 L J 0 O O O The secret character is a blocked character. Therefore, the key character generator must produce a throughput switching as follows:

Clear Character Key Character Secret Character 0 O Inversion) O L O Inversion) J O O Inversion) O The deciphering causes the following operations:

Secret Character Key Character Deciphered Result 0 O O J g L O O O 0 Key Character 0 Inversion) .l' O Inversion) L O 0 lnversion) 0 Secret Character Deciphered Result 0 0 There appears again the originally introduced clear character.

A possible form of circuitry for ternary systems, as just described, has been shown in principle in FIG. 3, whereby only the following essential elements have been illustrated.

a, b, c are the three primary storage contacts, which according to definition can each assume three positions.

s s s are three threefold contacts of the non-illustrated key character generator.

P, Q, R are polarized relays with central contact position. They operate as secondary storage means in conjunction with their holding contacts p, q, r and the cam contact n.,

The components 12 :1 r are switched together into a chain, they represent the OOO-detector of the secondary. signal and in this position excite the relay KK, which delivers to the non-illustrated generator the command key character 000 and delivers to the three switches designated lNV the command invert".

Finally, at 12 q r there appears the secondary character.

The person skilled in the art will understand from what has been stated above for a circuit construction explained in conjunction with a dual (binary) system quite readily the function of FIG. 3 (tertiary or ternary system) and can easily visualize the non-illustrated components which are still required, since they are in principle the same as shown therein.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

What is claimed is:

l. A device for enciphering or decipheringdata comprising an input location for receiving multi-digit coded characters, a key character generator for generating multidigit coded characters and a mixing stage connected to said input location and to said key character generator, said mixing stage having means for mixing character by character the multidigit coded characters from the input location with multidigit coded characters from the key character generator to generate an enciphered character, characterized in that the output of said key character generator is connected to a first character detector and the enciphered output of the mixing stage is connected to a second character detector wherein said first character detector upon detection of a first predetermined character combination (LLLLL or 000 respectively) causes said key character generator to shift until said key character generator generates a character combination differing from said first predetermined character combination and wherein said second character detector upon detection of a second predetermined character combination (00000 or 000, respectively) blocks the further transmission of said second character combination and causes said key character generator to generate said first, predetermined character combination (LLLLL or 000, respectively) and feeds said first character combination to said mixing stage bypassing said first character detector.

2. The device of claim 1 wherein said mixing means comprises means for combining the associated digit of the coded characters generated by said input means and said key character generator in an exclusive OR fashion. 

1. A device for enciphering or deciphering data comprising an input location for receiving multi-digit coded characters, a key character generator for generating multidigit coded characters and a mixing stage connected to said input location and to said key character generator, said mixing stage having meanS for mixing character by character the multidigit coded characters from the input location with multidigit coded characters from the key character generator to generate an enciphered character, characterized in that the output of said key character generator is connected to a first character detector and the enciphered output of the mixing stage is connected to a second character detector wherein said first character detector upon detection of a first predetermined character combination (LLLLL or 000 respectively) causes said key character generator to shift until said key character generator generates a character combination differing from said first predetermined character combination and wherein said second character detector upon detection of a second predetermined character combination (00000 or 000, respectively) blocks the further transmission of said second character combination and causes said key character generator to generate said first, predetermined character combination (LLLLL or 000, respectively) and feeds said first character combination to said mixing stage bypassing said first character detector.
 2. The device of claim 1 wherein said mixing means comprises means for combining the associated digit of the coded characters generated by said input means and said key character generator in an ''''exclusive OR'''' fashion. 